N-alkaline phosphatase activity in the peripheral blood lymphocytes and serum of a patient with malignant lymphoma and with cytochemically demonstrable lymphocyte alkaline phosphatase

Abstract

Twenty per cent of the circulating blood lymphocytes of a patient with non-Hodgkin's lymphoma expressed a positive alkaline phosphatase activity on cytochemical examination. The demonstrable alkaline phosphatase activity was localised on large lymphocytes which showed simultaneously scattered butyrate esterase and acid phosphatase positivity, surface membrane Ig, with multiple heavy chain isotypes but predominating κ light chains, and negative mouse erythrocyte rosetting. Alkaline phosphatase activity of the lymphocyte extracts of this patient was elevated 10-fold compared to that of normal lymphocyte extracts and did not catalyse the hydrolysis of cysteamine-S-phosphate, whereas the normal lymphocyte extracts did so with similar efficiency to the hydrolysis of p-nitrophenyl phosphate. These findings suggest that the lymphocytes of this patient contain an alkaline phosphatase (APase) isoenzyme different from that present in normal lymphocyte extracts. A Pase isoenzyme with similar catalytic properties was denoted previously N-phosphatase, N-A Pase. The extract of the patient's lymphocytes migrated on polyacrylamide gel to produce two A Pase activity bands; a slow-migrating weak band corresponding to the A Pase of normal lymphocyte extracts and a second faster-moving band, containing the major part of activity, corresponding to purified N-A Pase derived from Burkitt lymphoma cells. The serum of the same patient had a two-fold elevated A Pase activity compared to the upper limit of normal. N-A Pase composed 65–75% of the total A Pase activity.